Power supply system providing power and analog data signal for use by portable electronic device to control battery charging

ABSTRACT

A power supply system includes data circuitry as well as power circuitry to generate DC power for use by a portable electronic device having a rechargeable battery. The DC power, ground and two signaling lines are provided in a power supply connector which detachably mates with an electronic device power input port. In response to a first signal from the electronic device transmitted over one of the signaling lines, the data circuitry provides an analog signal to the electronic device over the other signaling line. The electronic device determines a parameter level, such as a current level, of the analog signal, and based on the determined parameter level controls charging of its battery.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 13/943,453,filed on Jul. 16, 2013, which is a continuation of application Ser. No.13/707,119, filed on Dec. 6, 2012, now U.S. Pat. No. 8,492,933 issued onJul. 23, 2013, which is a continuation of application Ser. No.13/209,636, filed on Aug. 15, 2011, now U.S. Pat. No. 8,330,303 issuedon Dec. 11, 2012, which is a continuation of application Ser. No.12/840,952, filed on Jul. 21, 2010, now U.S. Pat. No. 7,999,412 issuedon Aug. 16, 2011, which is a continuation of application Ser. No.11/604,950, filed on Nov. 28, 2006, now U.S. Pat. No. 7,868,486 issuedon Jan. 11, 2011, which is a continuation-in-part of application Ser.No. 10/758,933, filed on Jan. 15, 2004, now U.S. Pat. No. 7,453,171issued on Nov. 18, 2008.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to power supply equipment which includes anadapter and interchangeable tips. Via the tips, the power adapter isable to provide a data signal, as well as power, to various electronicdevices.

2. Description of the Related Arts

There are power systems in the art which allow a user to hook up a DC/DCadapter to an automobile outlet, to supply regulated DC power to poweran electronic device, such as a notebook computer. Automobile outletstypically provide a DC voltage in a range between 11.0 and 14.1 Volts.Some power systems also allow the user to hook up the DC/DC adapter toan airplane output such as the EMPOWER system. EMPOWER typicallyprovides a DC voltage in a range between 14.5 and 15.5 Volts.

Accordingly, some DC/DC adapters can be used with both an automobileoutlet and the EMPOWER system to provide a regulated DC power to theelectronic device such as the notebook computer. Notebook computersoften contain lithium ion batteries. Such batteries can be rechargedwhen the notebook computer is hooked up to the DC/DC adapter. Forexample, if the user is in a car, the user can couple a DC/DC adapter tothe notebook computer and to the cigarette lighter outlet to power thenotebook computer. The batteries in the notebook computer will draw someof the DC power supplied to recharge the batteries of the notebookcomputer if they are low in power. Accordingly, the user cansimultaneously use the notebook computer and recharge the batteriestherein.

The user can also use the DC/DC adapter while on an airplane, byplugging the DC/DC adapter into the EMPOWER outlet. The EMPOWER outletand the automobile outlets have different sizes and shapes. Accordingly,the user can directly plug the DC/DC adapter into the EMPOWER outlet,and can place a connector over the EMPOWER plug of the DC/DC adapter andthen plug the connector into the automobile cigarette lighter outlet.When the user hooks the DC/DC adapter up to the EMPOWER outlet and thento the electronic device, the electronic device receives the regulatedDC power. However, if the charging circuitry in the batterymalfunctions, the battery can overheat or even catch on fire whenrecharging from an EMPOWER DC source. If the battery were to catch onfire while an airplane in which the emPlower outlet is located isflying, the fire would have the potential to cause the airplane to crashor cause substantial damage.

To address this problem, one system in the art provides a connector toconnect between the DC/DC adapter and the notebook computer to informthe notebook computer not to recharge the batteries. FIG. 1 illustratesa power supply system according to the prior art. As shown, a DC powersource 100 is coupled to a DC/DC adapter 105 via a cable 102. The DC/DCadapter 105 receives power from the DC power source 100 and outputsregulated DC power to an electronic device 120, via a cable 110 and aconnector 115 coupled to the end of the cable 110.

The DC/DC adapter 105 can provide three output pins to the electronicdevice 120, as shown in FIGS. 2A and 2B of the prior art. The first pincan provide the output voltage (i.e., V_(out)), the second pin canprovide a ground reference (i.e., GND), and the third pin can provide adata line (i.e., V_(data)) to instruct the notebook as to whether thebatteries should be recharged or not. For example, as shown in FIG. 2A,V_(data) could be tied to GND to indicate that the DC power source 100is the EMPOWER system and therefore the battery should not be recharged.Alternatively, as shown in FIG. 2B, V_(data) could also be left open(i.e., to provide a non-grounded floating voltage) when the DC powersource 100 in a cigarette lighter outlet of an automobile. Accordingly,when using the DC/DC adapter 105 while in an automobile, the user woulduse a connector 115 having the V_(data) line floating, and when usingthe DC/DC adapter 105 with the EMPOWER system of an airplane, the userwould use a connector 115 having the V_(data) line tied to GND.

However, problems arise when the user forgets to change the connector115 for use with the automobile when the user is in an airplane.Accordingly, if the user has the wrong connector 115 attached when usingwith the EMPOWER system, a battery of an electronic device 120 such as anotebook computer can charge the battery even when used with the EMPOWERsystem, and if the charging circuitry of the battery malfunctions,overheating or even a fire can occur, resulting in damage to thenotebook computer. Also, if the connector 115 is damaged or flawed, thenit may not provide the correct V_(data) signal to the notebook computer,allowing the notebook computer to recharge the batteries in an airplanewhen they shouldn't be allowed to do so.

Accordingly, current DC/DC power adapter systems are deficient becausethey are incapable of automatically and intelligently informing anelectronic device 120 coupled thereto of the DC power source (i.e., theEMPOWER system or an automobile cigarette lighter outlet).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a power supply system according to the prior art;

FIG. 2A illustrates a first connector to coupled a power supply systemto an electronic device according to the prior art;

FIG. 2B illustrates a second connector to coupled a power supply systemto an electronic device according to the prior art;

FIG. 3 illustrates a power supply system according to an embodiment ofthe invention;

FIG. 4A illustrates a tip having digital control circuitry according toan embodiment of the invention;

FIG. 4B illustrates a tip having analog control circuitry according toan embodiment of the invention;

FIG. 5A illustrates comparison circuitry according to an embodiment ofthe invention;

FIG. 5B illustrates comparison circuitry according to an additionalembodiment of the invention;

FIG. 6 illustrates an electronic device according to an embodiment ofthe invention;

FIG. 7A illustrates a method of determining and outputting V_(data)according to an embodiment of the invention;

FIG. 7B illustrates a method of receiving V_(data) and allowing power toflow to devices within the electronic device based on V_(data) accordingto an embodiment of the invention;

FIG. 8 illustrates a power supply system according to an embodiment ofthe invention;

FIGS. 9A and 9B illustrate a tip including control circuitry accordingto embodiments of the invention;

FIG. 10 illustrates a tip including control circuitry and a measurementcircuit according to an embodiment of the invention; and

FIG. 11 illustrates a power supply system including a tip according toan embodiment of the invention.

DETAILED DESCRIPTION

An embodiment of the present invention is directed to a power supplysystem to determine a DC power source (e.g., an automobile cigarettelighter outlet or an EMPOWER airplane outlet) coupled thereto and send asignal indicative of the power source to an electronic device coupledthereto. The electronic device may be a notebook computer or otherportable consumer electronic device, for example. Based on the signalsent to the electronic device, the electronic device may control theamount of power drawn to prevent overheating. For example, when anotebook computer is hooked up and the power source is the EMPOWERsystem, the electronic device may disable charging of the internalbatteries of the notebook computer, in order to prevent damage oroverheating of the batteries due to malfunction or failure. The DC powersource may be determined by voltage comparison circuitry, such as acomparator, or by a voltage comparison device including a processor.

FIG. 3 illustrates a power supply system 301 according to an embodimentof the invention. As shown, the adapter 340 may be used with an AC powersource 300 or a DC power source 305. In other embodiments, only a DCpower source 305 may be utilized to supply power. The AC power source300 may be coupled to an AC/DC adapter 310 via a cable 342. The DC powersource 305 may be coupled to both a DC/DC adapter 315 and comparisoncircuitry 320 via a cable 345. The DC power source 305 may be anautomobile's cigarette lighter outlet or an airplane's EMPOWER systemoutlet, for example. AC/DC adapter 310 may convert AC power from the ACpower source 300 into regulated DC power, which is supplied topost-regulation circuitry 325. The post-regulation circuitry 325 mayprovide an output voltage (V_(out)) and a ground reference (GND) to atip 330 coupled to the adapter 340 via a cable 350, as further explainedbelow with respect to FIGS. 4A and 4B. The tip 330 may be coupled to anelectronic device 335 to provide the power thereto from the power supplysystem 301. The tip 330 may be removable from the cable 350 and may beinserted into a power input opening of the electronic device. Tips 330may have different shapes and sizes, depending up the shape and sizes ofthe power input openings of the respective electronic devices 335 beingpowered. The tip 330 may also include control circuitry 365 to provide asignal to control circuitry 370 of the adapter 340. The signal may besent to the control circuitry 370 via the cable 350. In one embodiment,the control circuitry 365 of the tip 330 may include digital componentsto provide a digital signal to the control circuitry 370 of the adapter340. The digital signal may be utilized to set the magnitude of V_(out)and limit the amount of current which may be drawn from the adapter 340.The post-regulation circuitry 325 regulates the voltage to what the tip330 tells it to provide.

Alternatively, the tip 330 may include analog components and may providevoltage programming and current programming voltages (V_(Vprogram) andV_(Iprogram), respectively) to the adapter 340. V_(Vprogram) may beutilized to set the magnitude of V_(out). For example, there may be alinear relationship between V_(Vprogram) and V_(out) where V_(out) is 3times as large as V_(Vprogram). Accordingly, if V_(Vprogram) had amagnitude of 3.0 Volts, V_(out) would have a magnitude of 9.0 Volts, andif V_(Vprogram) had a magnitude of 2.0 Volts, V_(out) would have amagnitude of 6.0 Volts. The analog circuitry may contain passive oractive components.

Accordingly, regardless of whether the tip 330 has analog or digitalcontrol circuitry, a single adapter 340 may be used to supply power to aplurality of different electronic devices 335 having different powerrequirements.

The adapter 340 may also include comparison circuitry 320. Thecomparison circuitry 320 may compare a magnitude of a voltage receivedfrom the DC power source 305 with a reference voltage to determinewhether the DC power source 305 is an automobile cigarette lighteroutlet or an EMPOWER airplane outlet. As stated above, automobilecigarette lighter outlets typically provide a DC voltage having amagnitude within the range of 11.0 Volts and 14.1 Volts. An EMPOWERairplane outlet typically provides a DC voltage having a magnitudewithin the range of 14.5 and 15.5 Volts. Accordingly, the referencevoltage may be set at a level between the high end of the automobilecigarette light outlet voltage (i.e., 14.1 Volts) and the low end of theEMPOWER airplane outlet voltage (i.e., 14.5 Volts). For example, thereference voltage may be set at 14.3 Volts. Accordingly, if themagnitude of the DC power source is greater than 14.3 Volts, then thecomparison voltage may determine that the received DC voltage has agreater magnitude than the reference voltage and the DC power source 305is therefore the EMPOWER airplane outlet. However, if the magnitude ofthe DC power source is less than 14.3 Volts, then the comparison voltagemay determine that the received DC voltage has a smaller magnitude thanthe reference voltage and the DC power source 305 is therefore theautomobile cigarette lighter outlet.

The comparison circuitry 320 may output a signal V_(data) based uponwhether the DC power source is determined to be the automobile cigarettelighter outlet or the EMPOWER airplane outlet. For example, thecomparison may output 5 Volts if the automobile cigarette lighter outletis detected, and 0.0 Volts if the EMPOWER airplane outlet is detected.In alternative embodiments, different voltages for V_(data) may be used.In additional embodiments, the comparison circuitry 320 may output adigital signal, such as a stream of bits, indicative of the DC powersource 305. V_(data) may be sent via cable 350 to the tip 330, andstraight over to the electronic device 335. The electronic device 335may include a controller 360 which is responsive to V_(data). Forexample, if the electronic device 335 is a notebook computer andV_(data) is indicative of the EMPOWER airplane outlet system, thecontroller 360 may disable battery charging circuitry 600, therebypreventing recharging of the batteries. And if the V_(data) isindicative of the automobile cigarette lighter outlet as the DC powersource 305, the controller 360 may enable battery charging circuitry toallow the batteries to be recharged.

Although FIG. 3 illustrates an adapter 340 which includes both a AC/DCadapter and a DC/DC adapter, other embodiments may include only a DC/DCadapter, and no AC/DC adapter.

FIG. 4A illustrates a tip 400 having digital control circuitry 402according to an embodiment of the invention. As shown, the tip 400receives V_(data), V_(out) and GND from the adapter 340 and allows themto all flow to the electronic device 335. The digital control circuitry402 may receive the V_(out) and GND signals and may output a controlsignal to the adapter 340 to set the magnitude of V_(out) and limit thecurrent provided. The control signal may be sent to the adapter 340 viathe cable 350 between the tip 400 and the adapter 340. The digitalcontrol circuitry 402 may include a processor and a memory device, forexample. In some embodiments, the tip 400 may be separable from cable350, and in other embodiments, the tip 400 may be physically part of thecable 350.

FIG. 4B illustrates a tip 405 having analog control circuitry 410according to an embodiment of the invention. As shown, the tip 405receives V_(data), V_(out) and GND from the adapter 340 and allows themto all flow to the electronic device 335. The analog control circuitry410 may receive the V_(out) and GND signals and may output V_(Vprogram)and V_(Iprogram) to the adapter 340. V_(Vprogram) and V_(Iprogram) maybe sent to the adapter 340 via the cable 350 between the tip 405 and theadapter 340. The analog control circuitry 400 may include passive oractive components, for example. In some embodiments, the tip 400 may beseparable from cable 350, and in other embodiments, the tip 400 may bephysically part of the cable 350.

FIG. 5A illustrates comparison circuitry 320 according to an embodimentof the invention. As shown, the comparison circuitry 320 includes acomparator 500. The comparator 500 receives (a) the DC power signal fromthe DC power source 305, and (b) a reference voltage, V_(ref). Thecomparator outputs V_(data) based on whether the magnitude of the DCpower from the DC power source exceeds V_(ref), as described above withrespect to FIG. 3.

FIG. 5B illustrates comparison circuitry 320 according to an additionalembodiment of the invention. As shown, the comparison circuitry 320includes a processor 505. The processor 505 receives (a) the DC powersignal from the DC power source 305, and (b) value of a referencevoltage stored in memory. The processor 505 then outputs V_(data) basedon whether the magnitude of the DC power from the DC power sourceexceeds V_(ref), as described above with respect to FIG. 3. Theprocessor 505 may output a single high or low voltage (e.g., 5.0 Voltsor 0.0 Volts) based on the detected DC power source. Alternatively, theprocessor 505 may output a stream of bits to indicate the DC powersource.

FIG. 6 illustrates an electronic device 335 according to an embodimentof the invention. As shown, the electronic device 335 may receive GND,V_(out) and V_(data) from the tip 330. V_(data) may be received by acontroller 360. The controller 360 may disable battery chargingcircuitry 600 of the electronic device 335 from charging batteries whenV_(data) is indicative of the EMPOWER outlet. Alternatively, thecontroller 360 enables battery charging circuitry 600 so that thebatteries of the electronic device may be charged based on the value ofV_(data).

FIG. 7A illustrates a method of determining and outputting V_(data)according to an embodiment of the invention. The processing shown inFIG. 7A may be implemented by the adapter 340. First, DC power isreceived 700 from the DC power source 305. Next, the comparisoncircuitry determines 705 whether the magnitude of the voltage of the DCpower received is greater than V_(ref). If “no,” the comparisoncircuitry determines the DC power source 305 to be an automobilecigarette lighter outlet, and processing proceeds to operation 710,where V_(data) is output with a signal/voltage magnitude indicating thatthe DC power source 305 is the automobile cigarette lighter outlet.Processing then returns to operation 700. If “yes,” at operation 705,processing proceeds to operation 715, where V_(data) is output with asignal/voltage magnitude indicating that the DC power source 305 is theEMPOWER airplane outlet.

FIG. 7B illustrates a method of receiving V_(data) and allowing power toflow to devices within the electronic device 335 based on V_(data)according to an embodiment of the invention. First, the electronicdevice 335 receives 720 the V_(data) signal. As discussed above, theV_(data) signal is sent from the adapter 340 through the tip 330 andover to the control circuitry 365 of the electronic device 335. Next,based on the V_(data) signal, a first set of predetermined devices maybe prevented 725 from receiving power. For example, if the electronicdevice 335 is a notebook computer, the control circuitry 365 may preventbatteries from recharging if V_(data) indicates that the DC power sourceis the EMPOWER airplane outlet. Other devices/components in theelectronic device 335 may also be prevented from receiving power or fromfunctioning in a certain way.

At operation 730, a second set of predetermined devices may be allowedto receive power based on the Vdata signal. For example, if V_(data)indicates that the DC power source is an automobile cigarette lighteroutlet, then power may be available to batteries of the electronicdevice 335 to allow recharging. Other devices/components in theelectronic device 335 may also be allowed to receive power or functionin a particular way.

In embodiments described above, the V_(data) signal may be used to senda signal to the control circuitry 365 indicating the DC power source.This signaling may be done via a discrete bit, an analog signal, a datasignal line, an analog voltage, or via any other suitable manner. TheV_(data) signal may be transmitted from the adapter 340 to the tip 330and electronic device 335 via a single signaling line or multiplesignaling lines.

FIG. 8 illustrates a power supply system 800 according to an embodimentof the invention. The power supply system 800 is similar to the powersupply system 301 shown in FIG. 3. However, unlike the power supplysystem 301, in which the adapter 340 itself contains comparisoncircuitry 370, the adapter 340 of power supply system 800 does notcontain the comparison circuitry 805. Instead, a regular adapter 340 maybe used and the electronic device 335 itself includes the comparisoncircuitry 805 for determining the DC power source. The electronic device335 may be a notebook computer and may implement the methods shown inFIGS. 7A and 7B.

FIG. 9A illustrates a tip according to an embodiment of the presentinvention. The tip 900 includes control circuitry 902 and a controller950. The tip 900 is coupled to an adapter 940 and may have a cabledisposed between the adapter 940 and the tip 900. The adapter 940transmits V_(out) and GND to the tip 900. In an embodiment of theinvention, digital or analog control circuitry 902 transmits aprogramming signal or a control signal to the adapter 940. In anembodiment of the invention, digital or analog control circuitry 902 maytransmit a plurality of programming signals to the adapter.Illustratively, digital or analog control circuitry 902 may transmit avoltage control signal to regulate the voltage output (Vout) from theadapter 940. The digital or analog control circuitry 902 may alsotransmit a current control signal to limit the current output from theadapter 940. The V_(out) and GND signals are passed through the adapter940 to the electronic device 935, such as a laptop, PDA, or cellularphone, to provide power to the electronic device.

In an embodiment of the invention, the tip 900 may also receive a value,which is illustrated by reference numeral 980 in FIG. 9A. The value maybe representative of whether or not the power adapter is an approvedadapter which can be connected to an electronic device 935. For example,for safety reasons, certain digital music player or laptop manufacturesonly desire to have certain manufacturers' power adapter connected totheir system. Accordingly, the power adapter may transmit a value thatindicates that the power adapter 940 is approved for powering theelectronic device. Alternatively, the value may be representative of amaximum power output that is available at the time from the poweradapter. For example, the value may represent that only 70 watts ofpower are available from the power adapter because the power adapter hasbeen limited to that output power. Instead of receiving a value from thepower adapter, the tip 900 may receive a character string. The characterstring may identify whether or not the power adapter is an approvedadapter for powering the electronic device 935. The value or thecharacter string may be received at input connector 985 of the tip 900.The input connector 985 may receive the value or character string andmay pass through this signal or information to the output connector 990.Under certain operating conditions, there may be no modification of thevalue or character string in the tip 900. The output connector 990 iscoupled to the electronic device 935 and passes the value or characterstring to the electronic device. A conductor 995 may couple the inputconnector 985 to the output connector 990.

FIG. 9B illustrates an alternative embodiment of a tip according to anembodiment of the invention. In an embodiment of the invention, the tip900 may include a controller 950, wherein the controller 950 includes areceiver 952, a memory 954, and a transmitter 956. In an alternativeembodiment of the invention, a programmable Dallas Semiconductorprogrammable memory (i.e., DS2502) may be substituted for a controllerand may include the receiver 952, memory 954, and transmitter 956. Thereceiver 952 may receive a signal from the electronic device 935. Thesignal may be a request from the electronic device 935 to interrogatethe tip 900 and identify whether or not an approved power adapter 940 iscoupled to the tip 900 and thus the electronic device 935. Once thecontroller 950 receivers the request from the electronic device 935, thecontroller 950 extracts a character string from the memory 954 andutilizes the transmitter 956 to transmit the character string to theelectronic device 935. The character string is representative of thepower adapter to which the tip 900 is coupled. In an embodiment of theinvention, a microcontroller may be programmed and could be utilized inplace of the transmitter 956, a receiver 952, and a memory 954. Thecharacter string may represent that the power adapter 940 and/or tip 900is approved to be connected to the electronic device, e.g. a laptop or acellular phone. Under certain operating conditions, the character stringrepresents that a rechargeable battery within the electronic device canbe charged by the power adapter 940 and tip 900 combination. Undercertain operating conditions, the character string is indicative of amaximum power available from the power adapter. Under certain operatingconditions, a value can be stored in the memory 954 where the value isindicative for the maximum power available from the power adapter.Illustratively, the value may be a power (or wattage) value or a currentvalue.

The transmitter 956 may communicate with the electronic device 935 via aone-wire interface. The transmitter 956 may communicate with theelectronic device 935 via other communication protocols, includingserial communication protocols.

FIG. 10 illustrates a second embodiment of a tip according to anembodiment of the invention. The tip 900 may include an analog ordigital control circuitry 910, a controller 950, and measurement circuit960 (e.g., a voltage sense circuit or a current sense circuit). Themeasurement circuit 960 may measure a magnitude level of a programmingor control signal e.g., (V_(Iprogram)), that is being transmitted to thepower adapter 940. In an embodiment of the invention, the programming orcontrol signal has a value representative of a maximum current availableto be output by the adapter 940. For example, a voltage magnitude of theprogramming or control signal identifies a value of current (e.g., inamperes) that the power adapter is available to output. Illustratively,each 0.5 volts in the programming or control signal may represent oneamp of current that the power adapter can output. A programming orcontrol signal having a magnitude of 2.5 volts represents that the poweradapter is limited to output 5 amperes and the power output is limitedto 100 watts (if the fixed voltage output is 20 volts). The measurementcircuit 960 may be implemented using a comparator or a number ofcomparators that compare a voltage level of the control signal to areference voltage level or a number of reference voltages.

In an alternative embodiment of the invention, the measurement circuit960 may be implemented by an analog-to-digital converter. Theanalog-to-digital converter may measure a value of the control signal orthe programming signal and identify the value which is representative ofthe power available to be output from the power adapter. In anembodiment of the invention, the analog-to-digital converter may be usedin conjunction with a microcontroller. The analog-to-digital convertermay be separate from the microcontroller or the analog-to-digitalconverter may be incorporated into the microcontroller.

The measurement circuit 960 takes the measured magnitude level of theprogramming or control signal and sends the information to thecontroller 950. A memory 954 may store a plurality of character strings.Alternatively, the memory 954 may store a plurality of values. Each ofthe plurality of character strings or values may represent a potentialpower output level of the power adapter 940. For example, one characterstring may be represent that the power adapter can output 90 watts whileanother character string represents that the power adapter can output140 watts. The controller 950 receives the magnitude level of theprogramming/control signal from the measurement circuit 960 and selectsthe corresponding character string stored in the memory 954.Alternatively, the controller receives the magnitude level of theprogramming or control signal and selects the corresponding value storedin the memory 954.

After the corresponding character string or value is selected, thecorresponding character string is transmitted to the electronic device935 through the transmitter 956. The electronic device receives thecharacter string and acts in response to the received character stringor value. For example, the character string may indicate that the poweradapter coupled to the tip (which is connected to the electronic device)can output 75 watts. Based on this information, a controller in anelectronic device 935 (e.g., a laptop) may prevent the power adapterfrom charging the rechargeable battery within the electronic device 935because the electronic device 935 may require all of the 75 watts ofpower.

The controller 950 may be a microcontroller. The controller 950including the receiver 952, transmitter 956, and memory 954 may be asemiconductor memory chip such as a Dallas Semiconductor DS2502programmable memory. The receiver 952 and transmitter 956 maycommunicate with the electronic device via a number of protocols, e.g.,the one-wire interface communication protocols, a serial interfacecommunication protocol, etc.

FIG. 11 illustrates an alternative embodiment of a power supply systemutilizing DC power source comparison circuitry according to anembodiment of the present invention. FIG. 11 is similar to the powersupply system illustrated in FIG. 3 and also includes a microcontroller950 in the tip 330. In FIG. 11, the microcontroller 950 receives asignal from the power adapter 340 in addition to the V_(out) signal andground signal. The power source determination signal may be referred toas a V_(data) signal and may be generated by the comparison circuitry320 in the adapter. The power source determination signal may identify apower capability of the external power source is an external automobileDC power source, an external AC power source, or an external airplane DCpower source. For example, the power source determination signal mayidentify that the power adapter is connected to an external airplane DCpower source and is limited to a number of watts of output, e.g., 50 or60 watts of power. Alternatively, the power source determination signalmay identify that the power adapter is connected to an externalautomobile power source, e.g., 90 watts or 100 watts.

The microcontroller 950 may receive the power source determinationsignal. Based on the received power source determination signal, themicrocontroller 950 may extract a character string corresponding to thereceived power source determination signal from a memory. The memory 954(see FIGS. 9A, 9B, and 10), as noted before, may store a number ofcharacter strings. Alternatively, the memory 954 may store a number ofvalues and the microcontroller 950 may select one of the number ofvalues. Although FIG. 11 does not illustrate that the microcontrollerincludes the memory 954, receiver 952, and transmitter 956, themicrocontroller 950 may incorporate these components. Alternatively, thememory 954, receiver 952, and transmitter 956 may be located in devicesoutside of the controller 950 (e.g., not incorporated therein). Thenumber of character strings or values may each represent a differentpower capability of the power adapters which can be coupled to the tipvia a cable. Illustratively, one character string or value may representa 90 watt power adapter, one character string may represent a 130 wattpower adapter, one character string may represent a 70 watt poweradapter, and one character string may represent that the power adapterhas a limited power supply capability, e.g., less than 70 watts.

In an embodiment of the invention, no character string or value may betransmitted if the power adapter cannot generate a certain wattage ofpower. This may represent that the power adapter and tip cannot beutilized to charge the battery of the electronic device. Themicrocontroller 950 may transmit the selected character string to theelectronic device. A controller 360 in the electronic device may receivethe selected character string and may perform a plurality of actionsbased on the selected character string. For example, if the selectedcharacter string identifies that the power adapter has a limited powercapability, e.g., less than 50 watts or 70 watts, the controller 360 mayplace the electronic device in a mode of low power consumptions, e.g.,turning off display earlier or not allowing charging of the battery inthe electronic device. Under other operating conditions, the characterstring or value may identify that an AC adapter is the external powersource and can provide 130 Watts, and the controller 360 may allow thebattery in the electronic device to be charged by the power adapter andplace the electronic device in a high power consumption mode, e.g.,brightness of screen and hard drive.

Under certain operating conditions, rather than a character string, themicrocontroller 950 may have a number of current levels that representdifferent power capabilities of adapters. Illustratively, in otherwords, a first current level may represent that the power adapter 340can supply 130 watts, a second current level may represent that thepower adapter 340 can supply 90 watts, a third current level representsthat the power adapter 340 can supply 70 watts, and a fourth currentlevel may represent the power adapter 340 supplies less that 70 watts.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention. The presently disclosedembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims, rather than the foregoing description,and all changes which come within the meaning and range of equivalencyof the claims are therefore intended to be embraced therein.

What is claimed is:
 1. A method of providing power to an electronicdevice comprising: detachably mating an output connector to theelectronic device; selecting a power adapter identification signalgenerated by one or more power adapter identification circuits, fortransmission to the electronic device via the output connector; sendingthe selected power adapter identification signal from the power adapteridentification circuit to the electronic device via the outputconnector; and selectively transmitting DC power to the electronicdevice via the output connector based on the selected power adapteridentification signal.
 2. The method of claim 1, wherein the poweradapter identification signal is selected by a user.
 3. The method ofclaim 1, wherein the power adapter identification signal is selected bythe configuration of a cable, the output connector, or the outputconnector adapter.
 4. The method of claim 3, wherein the configurationof the cable, output connector, or output connector adapter selectivelydetermines the transmission of a code which is sent from the outputconnector to a switching mechanism in the power adapter identificationcircuit.